Mercury switch



w. MURAD MERCURY SWITCH Dec. 24, 1940.

2 Sheets-Sheet 1 Original Fi led Jan. .27, 1931 INVENTOR. Vl a/fzrfiurad ATTORNEYS.

W. MURAD MERCURY SWITCH Dec. 24, 1940.

Originai Filed Jan. 27, 1951 2 Sheets-Sheet 2 )NVENTOR. %//Z/' Wurao ATTORNEYS;

Reiasued Dec. 24, 1940 UNITED STATES PATENT OFFICE MERCURY SWITCH Original No. 2,142,326, dated January 3, 1939,

SerlalNo. 511,537, January 27, 1931. Application for reissue July 20, 1940, Serial No. 346,664

12 Claims.

My invention relates to electric switches and is particularly applicable to a switch utilizing mercury or the like for controlling the opening and closing of the switch. i

Heretofore, electric switches suitable for gen eral domestic use, that is, switches for controlling the electrical circuits usually employed in and about places remote from the power station, have been objectionable on account of the local surges produced in the line upon operation of the switches. This characteristic is particularly objectionable when such switches are employed in the neighborhood of radio receiving sets or other electrically operated sound reproducing appa- 16 ratus, since the surges set up create disturbances in the apparatus. In order to prevent arcing at the contacts, switches heretofore employed have been designed to make and break thecircuit rapidly, a spring biased snap action being usually provided for effecting this result. The noise attendant upon the operation of such switches is not pleasant and frequently, as when the switches are employed in places-where silence is desired, this also is a source of annoyance.

It is a general object of my invention to provide a switch which is eflicient and reliable in operation.

Another object is to devise a switch in which means is provided ior opening and closing a circuit relatively gradually, thereby eliminating electrical surges.

Another object is to devise a switch in which means is provided for precluding arcing at the contacts and which is, nevertheless, silent in operation.

Another object is to provide a switch utilizing mercury or the like for breaking the circuit and in which the electrical connection between the contacts is made and broken in the body of mercury.

Still another object is to provide a switch which is simple and economical inconstruction.

A further object is to devise a novel method of manufacturing the switch of the present invention.

These and other objects and advantages are attained in the embodiments of my invention illustrated in the accompanying drawings, in

Fig. 3 is a front elevation of the switch with the cover removed'to show the construction.

Fig. 4 is a cross sectional view taken on line H of Fig. 3.

Fig.5 is a view showing certain details of the 5 device.

Fig. 6 is a cross sectional view of a modification in which the body of mercury employed in the switch remains relatively stationary and the contacts are movable into and out of engagement 10 with the mercury. In this figure one manner is illustrated in which a plurality of switches of the type disclosed can be mounted within a single housing. i

Fig. 'l is a cross sectional view taken on line 15 I'| of Fig. 6.

Fig. 8 is a cross sectional view taken on line 88 01' Fig. 7.

Fig. 9 is a perspective view of a detail.

In its preferred form the switch of my inven- 20 tion comprises a body of mercury which is adapted to be caused to flow into and out of engagement with one or more contacts of the switch to eil'ect opening and closing of the circuit controlled by the switch. Preferably, means is pro- 5 vided for making and breaking the circuit in the body of mercury, thereby causing any ,arcins which does take place to occur between two points in the mercury. Also, means can be provided for causing the circuit to be made and broken grad- 30 ually thereby eliminating electrical surges in the circuit.

Referring now to the drawings and first to Figs. 1 to 5 thereof, I have shown a switch of the wall type having a housing It formed of suitable 35 insulating material, such as porcelain, a phenol condensate product. or the like. A pair of brackets l1 and I6 can be provided each having one or more apertures therein for the reception of screws IQ for securing the housing to a wall or 40 other suitable support.

A pair of conducting brackets 2| and 22, each having an upstanding leg 23 and 24 preferably extending substantiallyperpendicular to the base of housing I8, are secured in any suitable manner 45 to the housing l6, as by means of screws 26. The brackets 2| and 22 are provided with binding posts 21 for connecting the switch in the electrical circuit which is to be controlled by the switch.

In the embodiment illustrated in Figs. 1 to 5, 5

the actuating member of the switch comprises a tumbler 28, mounted for rocking movement about an axis extending between the upper portions of legs 23 and 24. The tumbler 26 is preferably made hollow and is provided with a pair of con! stamped or otherwise formed therein ment 43. As shown engages both contacts 33 and 34 shown in Fig. 1, the mercury ducting plugs II and 32 extending from the interior of the tinnbler to the exterior thereof. The inner faces 33 and 34 of the plugs 3| and 32 constitute the contacts of the switch and in addition the plugs 3| and 32 can serve as trunnions for moimting the tumbler for rocking movement. For this purpose each of the plugs 3| and 32 is bevelled at its outer end, as at 38 and is journalled in a bearing formed in each of the legs 33 and 24. In the embodiment illustrated. the legs 23 and 24 have depressions 38 and 30 into which the bevelled ends 3' and 31, respectively, can extend. It is to be understood that if desired, any other suitable arrangement can be employed for journalling the tumbler for rocking movement. I have found, however, that the type of bearing shown gives good results, since wear is automatically taken up and good electrical contact between the plugs and the supporting brackets is provided at all times.

The tumbler 33 is preferably composed of moldable insulating material, such as a phenol condensate product, and the hollow compartment formed therein is shown as being divided into two parts 4| and 42 by a partitioning wall 43 through the handle of extending longitudinally the thumbler. A quantity of mercury 44 is disposed within the compartment and when the switch is mounted in operative position, the mercury can be caused to flow from one end of the tumbler to the other upon rocking movement thereof. For example, when the tumbler is rocked to the position illustrated in Fig. l, the mercury fiows to the outer end of the handle and when it is rocked Fig. 2, the mercury flows to the inner end.

When the tumbler 'is in the position shown in Fig. 2, the mercury takes the form of a single globule since the partitioning wall in the handle referably does not extend as far as the inner end wall of the compartment. When the tumbler is tilted to the position shown in Fig. 1, however, the mercury is divided into two parts bythe partitioning wall, one part flowing into compartment 4| and the other part flowing into compartin Figs. 2 and 4, when the mercury is at the inner end of the tumbler, it thereby serving to complete an electrical circuit in which these contacts may be included. It willalso be noticed that when the tumbler is rocked to the position flows away from the contacts thereby breaking thecircuit.

Preferably, the inner wall 43 is disposed between the contacts 33 and 34, asshown inl'igs.2and4,sothatasthemercury recedes from the inner end of the tumbler it is divided into two portions before it has left either one of the contacts 33 and 34. In a similar manner, when the mercury is flowing toward the contacts, the globule of mercury in compartment 4| makes engagement with contact 33 and the globule of mercury in compartment. 43 engages contact 34 before the two globules of mercury have reached the position where they flow together to form a single globule. By providingmeansofthischaract'erforpartingthe mercury upon openingthe switch before the mercury has left either contact and for caumng the mercury to make engagement with both of the contacts I3 and 34 before it is permitted to now together on theclosing of the switch. the circuit will be made and broken within the body of the the bearings need not be in the form of depressions and that tothepositionshownin edge of the partitioning 'edto'thedeslred mercury. Thus, no arcing can possibly occur at the surfaces of the contacts 33 and 34 and any arcing which may take place must occur in the body of the mercury.

The inner edge 45 of the partitioning wall 43 is preferably bevelled or sharpened and is in the form of a knife edge so thatat the instant the mercury is separated or reunited, as the case may be, the change is effected smoothly and gradually. As the mercury recedes from the contacts 33 and 34 upon tilting of the tumbler, theeil'ective cross section through the body of mercury decreases gradually, thereby increasing the resistance between the contacts. The rate of change in the cross section of the mercury during this movement can be accurately controlled bysuitably shaping the knife edge 45 and I have shown a curved portion 46 on the knife edge for this pur-' pose. Thus, the current in the circuit is gradually reduced to a minimum value before the circuit is finally broken. At the instant of final break, the current has reached its minimum value and any arcing which may occur will necessarily be of little consequence.

At the instant of separation, the surface tension of the mercury causes the separated globules to withdraw violently from one another, thereby abruptly breaking the circuit. Thus, not only is the arcing which, may occur of small magnitude, but it is also of extremely short duration. Experiments have shown that the amount of arcing is negligible in switches constructed in accordance with this invention and that the quality-of radio reception, for example, is not disturbed in Since the elimination of arcing in the present switch is not dependent upon the rapidity of movement of the actuating member, no provision need be made for biasing the member toward open and closed positions. The structure can be materially simplified, therefore, by omitting the usually complicated mechanism ordinarily employed for this purpose. Consequently, the switch is absolutely silent and free of all mechanical noises.

Suitable means can be provided, if desired, for retainin'gthe switch in either one or both of its operating positions. Thus, in Fig. 5 I have shown a flat surface 43 formed'on the bevelled end of trunnion 3| which is adapted to cooperate with a complementary fiat surface 4! in the bearing 38 for retaining the switch in one of its actuated positions. This expedient can also be employed in the other trunnion 32 to reinforce the holding eflect or, if desired, one of the trunnions can be provided with a surfacewhich serves to hold the switch "on while the other can have a surface to hold the switch off." For precluding oxidation or'other deterioration of the mercury, the tumbler 23 can be filled with some inert gas or, if desired, it can be partially evacuated. For ordinary conditio atmosphere of air gives very good results.

In manufacturing the tumbler II, I prefer to employ a moldable insulating material, such as a phenol condensate product, which can be moldshape directly above the trunnions 3i and 43 formed integrally within the handle of the tumbler. The open end of the tumbler can have secured therein, ilnofinsulating the compartment or bore within ns I have found that a rarefied 33 and with'the partitioning wallin any suitable'manner, a plug material having an l3 for evacuating the compartment after the mercury has been deposited. After the chamber has been evacuated sufllciently, the opening 52 can be sealed with sealing wax 83 or any other suitable non-conducting sealing material.

The preferred method of manufacture, however, is to heat the tumbler and the mercury which is placed therein, thereby expanding the tumbler and heating the air in the compartment.

" While the tumbler is still in heated condition, an unheated solid plug 54, shown in Fig. 4, can be forcibly inserted in' the open end of the tumbler. Upon cooling, the tumbler will contract about the plug, thereby holding it securely in place and the contraction of the air upon cooling will produce the desired rarefied atmosphere. Under some circumstances, I have found that the presence of a small amount of carbon in the mercury, in the neighborhood of about one per cent (1%), has a beneficial influence.

The legs 23 and 24 are formed of metal having good electrical conductivity and preferably having sufflcient resiliency to support the tumbler 28 without further aid. Brass or hard drawn copper are satisfactory, but it is to be understood that practically any other metal can be employed. In view of the inherentruggedness of the switch and the entire absence of breakable parts, the possibility of failure is extremely remote. However, if for any reason it is desired to replace the tumbler 28, the construction permits easy withdrawal thereof and a new tumbler can be readily snapped into place, thereby reconditioning the switch without disturbing any wiring in the circuit. The usual wall plate 58 can be disposed over the front side of the switch and secured thereto, as by means of screws 51. The tumbler 28 can have molded or otherwise formed thereon, suitable legends 58 to indicate the open or closed condition of the switch.

In the embodiment illustrated in Figs. 1 to 5 and which has been described above, it will be noticed that the mercury in flowing to and from the contacts changes its position relative to the axis of rotation of the tumbler 28. In Figs. 6 to 9, I have illustrated a modification in which the mercury remains substantially stationary relative to the axis of rotation of the actuating member while the switch contacts can be moved into and out of engagement with the mercury. The general principle of operation, however, is substantially the same as in the embodiment heretofore described.

Referring now to Figs. 6 to 8, I have shown a switch having a base I to which a pair of conducting brackets 82 and 63 are secured, as by means of screws M. The movable member 6 of the switch can be .of a general cylindrical shape and can have a compartment 81 therein. The member 88 is provided with trunnions 8! and II and is iournalled for rocking movement in bear-' ings 88 formed in or carried by the brackets 62 and II.

a The trunnions 88 and II are preferably made of conducting material and extend from the exterior of the member 8 into the compartment 81. Electrically connected to the trunnions are conducting strips 12 and 18 which can be disposed against opposite sides of the chamber 81. The strips 12 and I8 extend to a point near the peripheral wall of the chamber 61 and rotate with the member Ilas it is rocked from one position to another. I

- Ahuantityof mercury II is disposed within the compartment 61 and when the conducting strips I2 and I3 are rocked to the position shown in. Fig. 7, they are electrically connected together through the bod of mercury. Upon rocking the member 66 in a clockwise direction, as viewed in Fig. '7, the conducting strips 12 and 13 are withdrawn from the mercury, thereby opening the circuit. During this rocking movement, the mercury ll remains at the lower end of the compartment and-its position is substantially stationary relative to the axis of rotation of the member 65.

For parting the mercury 14 so that the circuit is made and broken within the body of the mercury, a severing member 16 is provided which has formed thereon one or more severing blades TI and 18. In the embodiment illustrated, two blades are shown, whereby the mercury is severed into three parts. The operation of the blades I1 and 18 is similar in every respect with the operation of the partitioning member 43, heretofore described in connection with the other embodiment.

For rotating member 66 a suitable handle 19 can be provided and if desired, suitable stops 8| and 82 can be provided on member 66 which are adapted to cooperate with a fixed stop 83 for limiting the rocking movement of member 68.

In Fig. 6 I have illustrated one manner in which a plurality of switches of the type described can be mounted within a single housing 84 for simultaneous operation. Thus, three, switches 86, 81 and 88 have been shown linked together, as by means of a bar 89, and are all operable upon actuation of a single handle 19. When all three switches are connected in parallel and to control the same circuit, the resulting switch is suitable for heavy duty, since the current in the circuit divides through the three switches. Also, by a similar construction, a multiple switch can be provided merely by shifting the phase relationship of the actuating members 86 on the different switches so that each switch operates in succession as theactuating handle 19 is moved from one of its extreme positions to the other. For example, the phase relationship between the switches can be such that the switch 86 closes when the handle is in its vertical position, as shown in Fig. 7, while switch 81 closes when the handle is thirty degrees removed from this position and switch 88 closes when the handle is sixty degrees removed from its original position, and all of the switches can be in open condition when the handle is in its horizontal position. In this manner any number of switches can be mounted for simultaneous operation and by suitably connecting the various switches into different electrical circuits, a wide variety of useful combinations can be produced.

While I have shown and described certain preferred. embodiments of my invention, I do not wish to be limited thereto, since the invention as defined in the appended claims canbe embodied in a phirality of other forms.

I claim:

1. In an electric switch, a housing having a recesstherein, means adjacent the front or said housing for mounting said housing on a support, a wall plate having an aperture therein, means for fastening said plate on said mounting means, resilient legs in said recess, and a tumbler insertible through said aperture and adapted to be gripped by said legs.

2.1!). an electric-switch, a housing having a recess therein, awall plate having an aperture 1 to overlie said recess,

therein adapted to overlie said recess. resilient legs in said recess, a tumbler partially disposedin said recess and projecting through said aperture,

an aperture therein adapted to overlie said frame,

cess, electrically conducting plugs in said tumbler, mercury partially filling said hollow tumbler and adapted to control electric flow throughi said plugs, and a pair of electrically conducting legs bler.

trically conducting legs in said recess, electrical terminals on said legs; a hollow tumbler adapted to pass bodily through said aperture and to be position of said tumbler for making and breaking an electrical circuit between said plugs.

'7. A switch comprising a wall plate adapted to be mounted substantially flush with the wall, a

projecting through said plate to provide a handle, said tumbler having a bore through its base portion and extending to its handle portion, contacts in the base, a body of mercury in the tumbler for trunnions, a body of mercury in the tumbler for bridging the contacts, and a fusible plug in the tumbler and closing said bore.

9. A switch comprising resilient brackets terminating in bearings, a hollow tumbler, trunnions on the tumbler journaled in the bracket bearings, contacts in the tumbler trunnions, a body of mercury in the tumbler for bridging the contacts, the bearing surfaces between the trunnions and brackets being tapered so that pulling on the tumbler causes the brackets to spring outwardly to releas the tumbler.

10. A mercury switch comprising a wall plate, a tumbler having a base portion positioned behind the wall plate and having an elongated portion projecting through the plate to provide a handle, said tumbler having a bore through its base to provide a mercury chamber, contacts in the base, a body of mercury in the tumbler for bridging the contacts, and a fusible plug in the base of the tumbler and closing said bore.

connected with said 11. In an electric switch, spaced contacts hav- 7' ing opposed surfaces, and a liquid contact circuit closer between said contacts and having terminals frictionally engaging said opposed surfaces, said terminals having complementary ball and socket portions whereby said circuit closer is rotatable about the axis of its terminals, the contacting surfaces of said portions being inclined with respect to the axis-of rotation of the circuit closer.

12. In an electric switch, a liquid contact circuit closer, and supports having opposed surfaces on opposite sides of said circuit closer, said surfaces and said circuit closer having complementary ball and socket portions whereby said circuit closer is rotatable about its axis, the con- .tacting surfaces of said portions being inclined with respect to t e axis of rotation of the circuit closer.

WALTER MURAD.

and said opposed surfaces 

